BACKGROUND/PURPOSE Friction blisters, a common injury in sports and military operations, can adversely effect or even halt performance. Given its frequency and hazardous nature, recent research efforts appear limited. Blistering can be treated as a delamination phenomenon; similar issues in materials science have been extensively investigated in theory and experiment. An obstacle in studying bl...

We used a robotic device to test the idea that impedance control involves a process of learning or adaptation that is acquired over time and permits the voluntary control of the pattern of stiffness at the hand. The tests were conducted in statics. Subjects were trained over the course of 3 successive days to resist the effects of one of three different kinds of mechanical loads: single axis lo...

Flexible pins eliminate the need for straddle mounting, and therefore enable the maximum possible number of planets to be used for any particular epicyclic ratio of power transmission systems. Having more planet gears will significantly increase the input torque density. In this type of design, the pin stiffness and position tolerances are important parameters as they affect the dynamic perform...

We consider the contact of two elastic bodies with rough surfaces at the interface. The size of the micro-peaks and -valleys is very small compared with the macrosize of the bodies’ domains. This makes the direct application of the FEM for the calculation of the contact problem prohibitively costly. A method is developed that allows deriving a macrocontact condition on the interface. The method...

This paper proposes a new impedance control algorithm based on a variable stiffness-matrix, for parallel-link manipulators without the measurement of the tip position. It assumes that only the link lengths and velocities as well as the contact force at the tip are measured, and that the motion range is small around an operating point so that the nonlinear dynamics can be linearized. One of the ...

A compliance control strategy for robot naanipulators is proposed in this paper by employing a selfadjusting stiffness function. To be specific, each entry of the diagonal stiffness rnatm”x corresponding to task coordinate in Cartesian space is adaptively adjusted during contact along the corresponding axis based on the contact force with its environment. And also, it can be used for both uncon...

This paper investigates simple implicit force control algorithms realizable with industrial robots. A lot of approaches already published are difficult to implement in commercial robot controllers, because the access to the robot joint torques is necessary or the complete dynamic model of the manipulator is used. In the past we already deal with explicit force control of a position controlled r...

We propose a new method for analyzing the stability of grasps. The characteristic points in this paper are to consider the curvature of both hand and object at contact points and the grasp with friction and frictionless contact. From this analysis, it is shown that the grasp using round fingers is more stable than using sharp fingers. Moreover, we establish the condition on the finger’s stiffne...

Cells in the central nervous system (CNS) respond to the stiffness of their environment. CNS tissue is mechanically highly heterogeneous, thus providing motile cells with region-specific mechanical signals. While CNS mechanics has been measured with a variety of techniques, reported values of tissue stiffness vary greatly, and the morphological structures underlying spatial changes in tissue st...

We studied the effect of delay on perception and action in contact with a force field that emulates elastic soft tissue with a rigid nonlinear boundary. Such field is similar to forces exerted on a needle during teleoperated needle insertion. We found that delay causes motor underestimation of the stiffness of this nonlinear soft tissue, without perceptual change. These experimental results are...